The present invention is directed to papers, and more specifically, to papers for electrography, such as xerographic compatible photographic papers, that is for example coated papers containing a supporting substrate derived from, for example, natural cellulose and having the appearance of a photographic base paper with certain coatings thereover and thereunder, and the use of these papers in imaging, especially xerographic processes and digital imaging processes, and wherein uniform high gloss images can be obtained. More specifically, the present invention is directed to processes for achieving loss uniformity of xerographic prints and which gloss is similar or equivalent to silver halide glossy prints or high quality glossy offset prints in color intensity and gloss uniformity with coated papers to which has been applied a substantially clear coating of a polyester resin, such as a low melt branched polyester, like the known SPAR polyesters, reference U.S. Pat. No. 3,590,000, the disclosure of which is totally incorporated herein by reference. The thin, for example from about 1 to about 10 microns, and preferably about 7 microns, or other suitable thickness, coating, especially the polyester coating, absorbs the fused toner particles thereby resulting in a smooth surface and high uniform gloss, and which gloss is less dependent on the degree of toner coverage. In embodiments, the coated photographic papers are capable of recording clear, brilliant, glossy images of high optical density, and with lightfastness values of greater than about 98 percent, and more specifically, from about 98 to about 100 percent for dry colored, such as pigmented toners, waterfastness values of about 100 percent and comparable in look and feel to conventional color photographic camera prints.
Certain polyester coated papers are known, reference for example U.S. Pat. Nos. 5,627,128; 5,534,479 and 4,692,636.
There is diclosed in U.S. Pat. No. 4,663,216 a synthetic paper comprised of (1) a multilayer support, (2) a layer of a transparent film of a thermophotographic resin free from an inorganic fine powder formed on one surface of the support (1), and (3) a primer layer of a specific material, reference the Abstract of the Disclosure for example. The support (1) comprises (1a) a base layer of a biaxially stretched film of a thermophotographic resin, a surface and a back layer (1b), and (1c) composed of a monoaxially stretched film of a thermophotographic resin containing 8 to 65 percent by weight of an inorganic fine powder.
Further, there is disclosed in U.S. Pat. No. 4,705,719 a synthetic paper of multilayer resin film comprising a base layer (1a) of a biaxially stretched thermophotographic resin film, and a laminate provided on at least one of opposite surfaces of the base layer, the laminate including a paper-line layer (1b) and a surface layer (1c), the paper like layer containing a uniaxially stretched film of thermophotographic resin containing 8 to 65 percent by weight of inorganic fine powder, and wherein the surface layer contains an uniaxially stretched film of a thermophotographic resin.
In U.S. Pat. No. 4,868,581, there is disclosed an opaque paper-based receiving material for ink jet printing which comprises a poly(olefin)-coated paper overcoated with an ink-receiving layer which contains a mixture of gelatin and starch. Reportedly, these receiving materials exhibit gloss, good color density and are smudge resistant. Although such receiving materials, when pictorially imaged with an ink jet printing device, may enable images acceptable in appearance and feel, the images thereon are still not believed to be of the same high quality that is customarily expected from and exhibited by photographic prints.
Also, there is disclosed in U.S. Pat. No. 4,903,039 an opaque paper-based receiving material for ink jet printing, which papers comprise a poly(olefin)-coated paper overcoated with an ink-receiving layer which contains an aqueous dispersion of a polyester ionomer, namely a poly[cyclohexylenedimethylene-co-oxydiethylene isophthalate-co-malonate-co-sodiosulfo benzenedicarboxylate], dispersed in vinyl pyrrolidone polymer.
Further, there is disclosed in U.S. Pat. No. 4,903,040 an opaque paper-based receiving material for ink jet printing which comprises a poly(olefin)-coated paper overcoated with an ink-receiving layer which contains an aqueous dispersion of a polyester ionomer, namely a poly[cyclohexylenedimethylene isophthalate-co-sodiosulfobenzene dicarboxylate], dispersed in vinyl pyrrolidone polymer.
Moreover, there is disclosed in U.S. Pat. No. 4,903,041 an opaque paper-based receiving material for ink jet printing which comprises a poly(olefin)-coated paper overcoated with an ink-receiving layer which contains an aqueous dispersion of a polyester ionomer, namely a poly[cyclohexylenedimethylene-co-xylyleneterephthalate-co-malonate-co-sodioiminobis(sulfonylbenzoate], dispersed in vinyl pyrrolidone polymer.
U.S. Pat. No. 5,451,458, the disclosure of which is totally incorporated herein by reference, discloses a recording sheet which comprises (a) a substrate; (b) a coating on the substrate which comprises (1) a binder selected from the group consisting of (A) polyesters; (B) polyvinyl acetals; (C) vinyl alcohol-vinyl acetal copolymers; (D) polycarbonates; and (E) mixtures thereof; and (2) an additive having a melting point of less than about 65xc2x0 C. and a boiling point of more than about 150xc2x0 C. and including, for example, furan derivatives; and developing the latent image with a toner which comprises a colorant and a resin selected from the group consisting of (A) polyesters; (B) polyvinyl acetals; (C) vinyl alcohol-vinyl acetal copolymers; (D) polycarbonates; and (E) mixtures thereof; and (3) transferring the developed image to a recording sheet which comprises (a) a substrate; (b) a coating on the substrate which comprises (1) a binder selected from the group consisting of (A) polyesters; (B) polyvinyl acetals; (C) vinyl alcohol-vinyl acetal copolymers; (D) polycarbonates; and (E) mixtures thereof.
While the above materials and processes may be suitable for their intended purposes, a need remains for photographic papers particularly suitable for use in electrophctogiaphic applications. In addition, a need remains for photographic papers which can be employed with xerographic dry toners so that the heat and energy required for properly fusing the toner to the photographic paper is reduced by about 14 percent allowing the toner to be fused, for example, at 150xc2x0 C. instead of the conventional about 175xc2x0 C. Further, a need remains for photographic papers which can be employed with xerographic toners, and wherein jamming of the photographic papers in the fusing apparatus is reduced. Additionally, there is a need for photographic papers suitable for use in electrophotographic applications with reduced energy demands, by about 14 percent, allowing the toner to be fused at 150xc2x0 C. instead of the usual in some instances of about 175 to about 180xc2x0 C., and reduced jamming, and wherein the photographs also exhibit acceptable image quality, excellent image fix to the paper, and more importantly, high uniform gloss similar to silver halide prints which typically have perfectly uniform high gloss levels of about 70 GU to about 100 GU as measured by a 75xc2x0 Glossmeter.
It is a feature of the present invention to provide photographic papers with many of the advantages indicated herein.
It is another feature of the present invention to provide photographic papers, inclusive of xerographic photopapers particularly suitable for use in electrophotographic imaging systems; and also wherein there are enabled developed images with uniform gloss, and wherein, for example, the coating on the paper, such as the polyoster illustrated herein, absorbs the fused toner particles thereby resulting in a smooth image surface.
It is yet another feature of the present invention to provide photographic papers which can be employed with xerographic dry toners, and wherein the heat and energy required for fusing the toner to the photographic paper is reduced, and wherein there are obtained images with uniform gloss throughout the visible image and which gloss is equivalent to, or similar to silver halide prints.
It is still another feature of the present invention to provide photographic papers which can be selected with xerographic dry toners, and wherein jamming of the photographic papers in the fusing apparatus is minimized.
Another feature of the present invention is to provide photographic papers suitable for use in electrophotographic, especially xerographic, imaging methods with reduced fusing energy requirements and reduced jamming, wherein the photographs also exhibit acceptable image quality, excellent image fix to the photographic papers, and superior gloss.
The present invention relates to a coated photographic paper comprised of (1) a substrate, such as a cellulosic substrate, and a coating thereover of a polyester or similar polymer and which coating is preferably thin, for example about 1 to about 15, or from about 5 to about 10 microns, as measured by a thickness gauge, model MT-12 from Heidenhain, and wherein there is enabled uniform glossy images with such papers. More specifically, there are provided in accordance with the present invention processes for generating high, for example, from about 50 to about 100 gloss units as s measured with a 75xc2x0 Glossmeter, Glossgard from Pacific Scientific, and which gloss is uniform, that is it does not significantly vary, or change on the image, or wherein the differential gloss level is reduced or minimized, that is for example, a gloss variance of about 40 GU to about 80 GU is a with the invention polyester coated papers. By uniform gloss is meant, for example, a gloss variation of between about 20 GU to about 10 GU and preferably a gloss variation of between about 10 GU to about 0 GU.
Aspects of the present invention relate to a process which comprises forming an image on a substrate, and developing the image with toner, and wherein the substrate contains a coating of a polyester and there is is enabled images of uniform gloss; a process wherein the polyester coating is of a thickness of about 1 to about 15 microns; a process wherein the polyester coating is of a thickness of about 7 microns; a process wherein the polyester coating is a poly(propoxylated bisphenol A fumarate) resin, a polyester resin of a terephthalic acid, bisphenol-A-ethylene oxide adduct, cyclohexane dimethanol or a low, from about 1,000 to about 50,000 MW, molecular weight, branched copolyester formed from isophthalic and nonanedioic acids with diols and triols; a process wherein the gloss value is high, and wherein said high is between about 50 GU to about 100 GU as measured by a 75xc2x0 Glossmeter; a process wherein the gloss value is high, and wherein said high is between about 80 GU to about 100 GU as measured by a 750 Glossmeter, and which gloss is the same or similar throughout the entire developed image; a process wherein the substrate is of a thickness of from about 80 microns to about 200 microns; a process wherein the uniform high gloss resides in substantially no gloss difference in the range of gloss of 70 GU to 100 GU, and wherein said gloss is equivalent to or similar to silver halide prints; a process wherein the substrate is a cellulosic substrate and is comprised of alkaline sized and acid sized blends of hardwood kraft and softwood kraft fibers, which blends contain from about 10 percent to about 90 percent by weight of softwood and from about 90 to about 10 percent by weight of hardwood; a process wherein the sizing value of the cellulosic substrate is from about 200 seconds and about 1,100 seconds, the porosity is from about 50 to about 300 mil/minute, and the thickness is from about 50 microns and about 250 microns; an imaging process which comprises (1) generating an electrostatic latent image on an imaging member in an imaging apparatus; (2) developing the latent image with a toner comprised of a colorant and a resin, such as a known thermoplastic resin, and more specifically, binder resin selected from the group consisting of (A) polyesters, (B) styrene-butadiene copolymers, (C) styrene-acrylate copolymers, and (D) styrene-methacrylate copolymers; (3) transferring the developed image to a coated paper and wherein the coating is a polyester; and (4) fixing the image onto the paper with heat and pressure; an imaging process wherein the images resulting on a polyester coated substrate, such as paper possess an optical density between about 1.45 to about 1.56 for a black toner, between about 1.35 to about 1.40 for a cyan toner, between about 1.23 to about 1.30 for a magenta toner, and between about 0.87 to about 0.89 for a yellow toner; an imaging process wherein the colorant is a pigment and the resin is a polyester; an imaging process wherein the colorant is a dye; a process which comprises forming an image on a coated substrate, and developing the image with a toner, and wherein the substrate contains a polymer coating and there is enabled images of a high uniform gloss; a process wherein the coating is a polyester, a process wherein the substrate is paper or coated reproduction paper having a thickness in the range of about 80 microns to about 200 microns; a process wherein the toner is comprised of resin and colorant; a process wherein the resin is a polyester of poly(propoxylated bisphenol A fumarate), a polyester resin comprised of terephthalic acid/bisphenol A ethylene adduct/cyclohexane dimethanol or low molecular weight, branched copolyesters formed from isophthalic and nonanedioic acids with diols and triols; a process wherein the toner is comprised of resin and colorant; a photopaper comprised of a substrate and a thin coating thereover, and wherein said thin coating is from about 1 to about 20 microns, and wherein a photopaper is selected for the generation of images with a uniform gloss; a photopaper wherein sad coating is a polyester wherein said images are developed with a toner of resin and colorant, and wherein said polyester possesses a lower melt viscosity than the toner resin at the temperature used to fuse said images, and wherein the melt viscosity of the polyester coating is from about 500 poise to about 1,000 poise, and the melt viscosity of the toner resin is from about 4,000 poise to about 5,000 poise; a process wherein the gloss variation is between about 20 GU to about 10 GU, or the gloss variation is between about 10 GU to about 0 GU as measured by a 75xc2x0 Glossmeter; a process wherein the gloss variation is between about 10 GU to about 0 GU as measured by a 75xc2x0 Glossmeter; a process wherein the toner image is absorbed into the substrate coating during the fusing process; a process which comprises forming an image on a substrate, and developing the image with toner, and wherein the substrate contains a coating of a polyester; an imaging process which comprises (1) generating an electrostatic latent image on an imaging member in an imaging apparatus; (2) developing the latent image with a toner which comprises a colorant and a resin; (3) transferring the developed image to a polyester coated substrate; and (4) fixing the image onto the paper with heat and pressure; and a process wherein polyester diols are 2,2,4,4-tetraalkyl-1,3-cyclobutane diol, 1,4-butane diol, or 1,3-propane diol; and wherein the triols are 2-(hydroxy methyl)1,3-propane diol, 1,1,1 (trishydroxy methyl) ethane, 1,2,4-butane triol, or 1,2,3-propane triol.
The substrates selected are primarily coated papers comprised of a photopaper of a base sheet and commercially available as ink jet, off set or xerographic papers, and wherein there is applied to the paper by solvent coating thereof a polymer, preferably a polyester, and wherein there is selected a dry toner for development, and more specifically, a toner containing a polyester resin. The coating, such as the polyester, applied to the paper preferably possesses a lower melt viscosity at the image fusing temperature of, for example, about 140xc2x0 C. to about 170xc2x0 C. than the toner resin, especially toner polyester resin. By lower melt viscosity is meant, for example, a viscosity of, for example, about 500 poise to about 1,000 poise and preferably about 500 poise to about 700 poise as measured by a Rheometrics Dynamic Mechanical Spectrometer. The coated substrate, such as paper, is more specifically comprised of a coated reproduction paper where the manufacturers coating is believed to comprise from about 70 percent by weight to about 90 percent by weight of a pigment, such as Kaolin clay, calcined clays, calcium carbonate, titanium dioxide, talc or alumina trihydrate, and about 5 to about 30 weight percent of a binder, such as starch, poly(vinyl alcohol), styrene-butadiene, polyacrylate or poly(vinyl acetate). These coated reproduction papers are available from paper manufacturers, such as the Champion Paper Company, Consolidated Papers Inc., Asahi Glass Company and Schoeller Papers Inc. Suitable coated reproduction papers have thicknesses ranging from, for example, about 80 microns to about 200 microns. The coating, such as preferably the polyester coating, is more specifically comprised of a poly(propoxylated bisphenol A fumarate) resin, a polyester resin comprised of poly(terephthalic acid bisphenol-A-ethylene oxide adduct), cyclohexane dimethanol or a low, for example from about 1,000 to about 50,000, and preferably about 20,000 MW molecular weight, branched copolyester formed from isophthalic and nonanedioic acids with diols and triols, such as resin, is Vitel 5833B polyester available from the Bostik Company. Other suitable coatings may be selected, such as known polyesters, inclusive of the polyesters of, for example, U.S. Pat. No. 3,590,000.
Any suitable substrate can be employed; for example, the substrate can be comprised of sized blends of hardwood kraft and softwood kraft fibers, which blends contain from about 10 percent to about 90 percent by weight of softwood and from about 90 to about 10 percent by weight of hardwood. Examples of hardwood include Seagull W dry bleached hardwood kraft preferably present, for example, in one embodiment in an amount of about 70 percent by weight. Examples of softwood include La Toque dry bleached softwood kraft present, for example, in one embodiment in an amount of 30 percent by weight. These sized substrates may also contain pigments in effective amounts of from about 1 to about 60, and preferably from about 1 to about 25 percent by weight, such as clay (available from Georgia Kaolin Company, Astro-fil 90 clay, Engelhard Ansilex clay), titanium dioxide (available from Tioxide Companyxe2x80x94Anatase grade AHR), calcium silicate CH-427-97-8, XP-974 (J. M. Huber Corporation), and the like. Also, the sized substrates may contain various effective amounts of sizing chemicals (for example from about 0.25 percent to about 25 percent by weight of pulp), such as Mon size (available from Monsanto Company), Hercon-76 (available from Hercules Company), Alum (available from Allied Chemicals as Iron free alum), and retention aid (available from Allied Colloids as Percol 292). The sizing values of papers, including the commercial papers that can be selected for the present invention in embodiments thereof, vary between, for example, about 0.4 second to about 4,685 seconds, and papers in the sizing range of about 50 seconds to about 300 seconds are preferred, primarily to decrease costs. The porosity values of the substrates, which are preferably porous, vary from about 100 to about 1,260 mil/minute and preferably from about 100 to about 600 mil/minute to permit, for example, the use of these papers for various printing technologies, such as thermal transfer, liquid toner development, xerography, ink jet processes, and the like.
Illustrative examples of commercially available, internally and externally (surface) sized substrates that may be selected for the present invention, and which are treated with a desizing agent dispersed in an optional binder with a substrate thickness of, for example, from about 50 microns to about 200 microns and preferably of a thickness of from about 100 microns to about 175 microns include Diazo papers, offset papers such as Great Lakes offset, recycled papers such as Conservatree, office papers such as Automimeo, Eddy liquid toner paper and copy papers from companies such as Nekoosa, Champion, Wiggins Teape, Kymmene, Modo, Domtar, Veitsiluoto and Sanyo with Xerox 4024(trademark) papers and sized calcium silicate-clay filled papers being particularly preferred in view of their availability, and low print through.
The Hercules size values recited herein were measured on the Hercules sizing tester (available from Hercules Incorporated) as described in TAPPI STANDARD T-530 pm-83, issued by the Technical Association of the Pulp and Paper Industry. This method is closely related to the widely used ink flotation test. The TAPPI method has the advantage over the ink flotation test of detecting the end point photometrically. The TAPPI method employs a mildly acidic aqueous dye solution as the penetrating component to permit optical detection of the liquid front as it moves through the paper sheet. The apparatus determines the time required for the reflectance of the sheet surface not in contact with the penetrant to drop to a predetermined (80 percent) percentage of its original reflectance.
The coated xerographic photographic papers of the present invention exhibit reduced curl upon being printed with toners. Generally, the term xe2x80x9ccurlxe2x80x9d refers to the distance between the base line of the arc formed by recording sheet when viewed in cross-section across its width (or shorter dimension, for example 8.5 inches in an 8.5 by 11 inch sheet, as opposed to length, or longer dimension, for example 11 inches in an 8.5 by 11 inch sheet) and the midpoint of the arc. To measure curl, a sheet can be held with the thumb and forefinger in the middle of one of the long edges of the sheet (for example, in the middle of one of the 11 inch edges in an 8.5 by 11 inch sheet) and the arc formed by the sheet can be matched against a pre-drawn standard template curve.
The lightfastness values of the xerographic images were measured in the Mark-V Lightfastness Tester obtained from Microscal Company, London, England.
The gloss values recited herein were obtained on a 75xc2x0 Glossmeter, Glossgard, from Pacific Scientific (Gardner/Neotec Instrument Division). The edge raggedness values were measured using an Olympus microscope equipped with a camera capable of enlarging the recorded xerographic images. The edge raggedness value is the distance in millimeters for the intercolor bleed on a checkerboard pattern.
The optical density measurements recited herein were obtained on a Pacific Spectrograph Color System. The system consists of two major components, an optical sensor and a data terminal. The optical sensor employs a 6 inch integrating sphere to provide diffuse illumination and 2 degrees viewing. This sensor can be used to measure both transmission and reflectance samples. When reflectance samples are measured, a specular component may be included. A high resolution, full dispersion, grating monochromator was used to scan the spectrum from 380 to 720 nanometers. The data terminal features a 12 inch CRT display, numerical keyboard for selection of operating parameters, and the entry of tristimulus values, and an alphanumeric keyboard for entry of product standard information. The print through value as characterized by the printing industry is Log base 10 (reflectance of a single sheet of unprinted paper against a black background/reflectance of the back side of a black printed area against a black background) measured at a wavelength of 560 nanometers.
A number of different toners can be selected. Illustrative examples: of suitable toner binders are, for example, resins such as polyesters, polyamides, polyolefins, styrene acrylates, styrene methacrylate, styrene butadienes, crosslinked styrene polymers, epoxies, polyurethanes, vinyl resinis, including homopolymers or copolymers of two or more vinyl monomers; and polymeric esterification products of a dicarboxylic acid and a diol comprising a diphenol. Vinyl monomers include styrene, p-chlorostyrene, unsaturated mono-olefins such as ethylene, propylene, butylene, isobutylene and the like; saturated mono-olefins such as vinyl acetate, vinyl propionate, and vinyl butyrate; vinyl esters like esters of monocarboxylic acids including methyl acrylate, ethyl acrylate, n-butylacrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate; acrylonitrile, methacrylonitrile, acrylamide; mixtures thereof; and the like, styrene butadiene copolymers with a styrene content of from about 70 to about 95 weight percent. In addition, crosslinked resins, including polymers, copolymers, homopolymers of the aforementioned styrene polymers may be selected.
As one toner resin, there are selected the esterification products of a dicarboxylic acid and a diol comprising a diphenol. These resins are illustrated in U.S. Pat. No. 3,590,000, the disclosure of which is totally incorporated herein by reference. Other specific toner resins include styrene/methacrylate copolymers, and styrene/butadiene copolymers; PLIOLITES(copyright); suspension polymerized styrene butadienes, reference U.S. Pat. No. 4,558,108, the disclosure of which is totally incorporated herein by reference; polyester resins obtained from the reaction of bisphenol A and propylene oxide; followed by the reaction of the resulting product with fumaric acid, and branched polyester resins resulting from the reaction of dimethylterephthalate 1,3-butanediol, 1,2-propanediol, and pentaerythritol, styrene acrylates, and mixtures thereof. Also, waxes with a molecular weight, Mw of from about 1,000 to about 20,000, such as polyethylene, polypropylene, and paraffin waxes, can be included in, or on the toner compositions as fuser roll release agents. Also, it is preferred that the, toner resin be the same as, or similar to the substrate coating.
The resin particles are present in a sufficient, but effective amount, for example from about 70 to about 90 weight percent. Thus, when 1 percent by weight of a charge enhancing additive is present, and 10 percent by weight of pigment or colorant, such as carbon black, is contained therein, about 89 percent by weight of resin is selected.
Numerous well known suitable colorants, such as pigments or dyes, can be selected as the colorant for the toner particles including, for example, carbon black, nigrosine dye, aniline blue, magnetite, or mixtures thereof. The colorant, which can be carbon black, cyan, magenta, yellow, red, green, blue, brown, pink, orange, mixtures thereof and the like should be present in a sufficient amount to render the toner composition colored. Generally, the colorant is present in amounts of from about 1 percent by weight to about 20 percent by weight, and preferably from about 2 to about 10 weight percent based on the total weight of the toner composition; however, lesser or greater amounts can be selected. Illustrative examples of magentas include, for example, 2,9-dimethyl-substituted quinacridone and anthraquinone dye identified in the Color Index as CI 60710, CI Dispersed Red 15, diazo dye identified in the Color Index as CI 26050, CI Solvent Red 19, and the like. Illustrative examples of cyans include copper tetra-4-(octadecyl sulfonamido) phthalocyanine, X-copper phthalocyanine pigment listed in the Color Index as CI 74160, CI Pigment Blue, and Anthrathrene Blue, identified in the Color Index as CI 69810, Special Blue X-2137, and the like; while illustrative examples of yellows are diarylide yellow 3,3-dichlorobenzidene acetoacetanilides, a monoazo pigment identified in the Color Index as CI 12700, CI Solvent Yellow 16, a nitrophenyl amine sulfonamide identifiers in the Color Index as Foron Yellow SE/GLN, CI Dispersed Yellow 33, 2,5-dimethoxy-4-sulfonanilide phenylazo-4xe2x80x2-chloro-2,5-dimethoxy acetloacetanilide, and Permanent Yellow FGL.
When the colorant particles are comprised of magnetites, thereby enabling single component toners in some instances, which magnetites are a mixture of iron oxides (FeO.Fe2O3) including those commercially available as MAPICO BLACK(copyright), they are present in the toner composition in an amount of from about 10 percent by weight to about 70 percent by weight, and preferably in an amount of from about 10 percent by weight to about 50 percent by weight. Mixtures of carbon black and magnetite with from about 1 to about 15 weight percent of carbon black, and preferably from about 2 to about 6 weight percent of carbon black, and magnetite, such as MAPICO BLACK(copyright), in an amount of, for example, from about 5 to about 60, and preferably from about 10 to about 50 weight percent can be selected.
There can also be blended with the toner compositions of the present invention external additive particles including flow aid additives, which additives are usually present on the surface thereof. Examples of these additives include colloidal silicas such as those available from DeGussa Chemicals, AEROSIL(copyright), metal salts and metal salts of fatty acids inclusive of zinc stearate, aluminum oxides, titanium oxides, titanates like stronium titanate, cerium oxides, and mixtures thereof, which additives are each generally present in an amount of from about 0.1 percent by weight to about 5 percent by weight, and preferably in an amount of from about 0.1 percent by weight to about 1 percent by weight. Several of the aforementioned additive are illustrated in U.S. Pat. Nos. 3,590,000 and 3,800,588, the disclosures or which are totally incorporated herein by reference.
Moreover, there can be included in the toner compositions of the present invention low, such as from about 1,000 to about 20,000 Mw, molecular weight waxes, such as polypropylenes and polyethylenes commercially available from Allied Chemical and Petrolite Corporation, Epolene N-15 commercially available from Eastman Chemical Products, Inc., Viscol 550-P, a low weight average molecular weight polypropylene available from Sanyo Kasei K.K., and similar materials. The commercially available polyethylenes selected have a molecular weight of from about 1,000 to about 1,500, while the commercially available polypropylenes utilized for the toner compositions of the present invention are believed to have a molecular weight of from about 4,000 to about 5,000. Many of the polyethylene and polypropylene compositions useful in the present invention are illustrated in British Patent No. 1,442,835, and U.S. Pat. No. 5,229,242, the disclosures of which are totally incorporated herein by reference.
The low molecular weight wax materials are present in the toner composition of the present invention in various amounts, however, generally these waxes are present in the toner composition in an amount of from about 1 percent by weight to about 15 percent by weight, and preferably in an amount of from about 2 percent by weight to about 10 percent by weight.
For the formulation of developer compositions, there are mixed with the toners carrier components, particularly those that are capable of triboelectrically assuming an opposite polarity to that of the toner composition. Accordingly, the carrier particles can be selected to be, for example, of a negative polarity enabling the toner particles, which are positively charged, to adhere to and surrond the carrier particles. Illustrative examples of carrier particles include iron powder, steel, nickel, iron, ferrites, including copper zinc ferrites, and the like. Additionally, there can be selected as carrier particles nickel berry carriers as illustrated in U.S. Pat. No. 3,847,604, the disclosure of which is totally incorporated herein by reference. The selected carrier particles can be used with or without a coating, the coating generally containing terpolymers of styrene, methylmethacrylate, and a silane, such as triethoxy silane, reference U.S. Pat. Nos. 3,526,533 and 3,467,634, the disclosures of which are totally incorporated herein by reference; polymethyl methacrylates; other known coatings; and the like. The carrier particles may also include in the coating, which coating can be present in one embodiment in an amount of from about 0.1 to about 3 weight percent, conductive substances, such as carbon black, in an amount of from about 5 to about 30 percent by weight. Polymer coatings not in close proximity in the triboelectric series can also be selected, reference U.S. Pat. Nos. 4,937,166 and 4,935,326, the disclosures of which are totally incorporated herein by reference, including for example KYNAR(copyright) and polymethylmethacrylate mixtures (40/60). Coating weights can vary as indicated herein; generally, however, from about 0.3 to about 2, and preferably from about 0.5 to about 1.5 weight percent coating weight is selected.
The diameter of the carrier particles, preferably spherical in shape, is generally from about 50 microns to about 1,000, and more specifically, from about 75 to about 150 microns thereby permitting them to possess sufficient density and inertia to avoid adherence to the electrostatic images during the development process. The carrier component can be mixed with the toner composition in various suitable combinations, however, best results are obtained when about 1 to 5 parts per toner to about 100 parts to about 200 parts by weight of carrier are selected.
Specific embodiments of the invention will now be described in detail. These Examples are intended to be illustrative, and the invention is not limited to the materials, conditions, or process parameters set forth in these embodiments. All parts and percentages are by weight unless otherwise indicated. Comparative Examples and data are also provided.
The variation in gloss level of a xerographic color print can be quantified by using a specially devised differential gloss test target. The test target consists of an 8 and xc2xd by 11 inch sheet having nine equally sized squares of 5 centimeter dimension evenly spaced around the area of the sheet. The nine squares have varying optical density which is achieved by varying the toner coverage on each square as follows: 0 percent coverage (substrate only), 10 percent coverage, 20 percent coverage, 40 percent coverage, 60 percent coverage, 80 percent coverage, 100 percent coverage, the color green (2 layers of toner) and process black (3 layers of toner). A print of this test target is then produced on a xerographic color copier/printer using a given substrate. The gloss level of the nine squares on the resulting xerographic print is measured using a 75xc2x0 Glossmeter. The variation in gloss level is then defined as the difference in gloss between the highest and lowest gloss values obtained from the nine squares of varying toner coverage.
The Xerox Corporation 5790 toner set used in the following Examples was comprised of a terephthalic acid, bisphenol-A-ethylene adduct, cyclohexane dimethanol polyester resin, and each of the toners had the following compositions. The cyan toner was composed of 95.5 percent (by weight throughout) of the polyester resin and 4.5 percent of C.I. Pigment Blue 15:3: the magenta toner was composed of 94 percent of the polyester resin and 6 percent of C.I. Pigment Red 57:1; the yellow toner was composed of 92.8 percent of the polyester resin and 7.2 percent of C.I. Pigment Yellow 17; and the black toner was composed of 94 percent of the polyester resin and 6 percent of carbon black #25B from the Mitsubishi Kasei Corporation.